Mold engraving machine



Oct. 21, 1952 A, H, IEH 2,614,464

MOLD ENGRAVING MACHINE Filed April 21, 1948 7 Sheets-Sheet 5 FIG. 3

A TTORNEYJ I Oct. 21, 1952 A. H. KlEHL MOLD ENGRAVING MACHINE 7 Sheets-Sheet 4 Filed April 21, 1948 M u 8 H H 5 w M R 0 m K n M A v H m Y m B 0 W 1/ fin /l I I m. J ow T Q: .7: f, m M mm. 0mm M2 m. 2mm. m5 09 mm 0E $5M Om; mm. 09 5. av 9 m 5 Q3 0a mom ll-i 1 I l w! n mwu Na 1 3% m3 5 c m M NMM PIN MOM u 1mm mmm :mu :3 oou o EN 3 "I.. u mmm Eu 5N A.'H. KIEHL MOLD ENGRAVING MACHINE Oct. 21, 1952 '7 Sheets-Sheet 5 Filed April 21, 1948 BY w'zk ATTORNEYS Oct. 21, 1952 Y A. H. KlEHL 2,614,464

MOLD ENGRAVING MACHINE Filed April 21, 1948 7 Sheets-Sheet 6 IN VEN TOR fiRTHL/F H K/EHL A TTORNEYJ Oct. 21, 1952 A. H. KlEHL MOLD ENGRAVING MACHINE 7 Sheets-Sheet '7 Filed April 21. 1948 shown and described but the machine may be modified or improved without sacrificing any of the essential features of the invention as set forth in the appended claims.

In the drawings:

Fig. l is a side elevation of the machine constituting the preferred embodiment of the invention. In this view the parts of the machine constituting the drive for the table are shown in section;

Fig. 2 is a plan view of the forward portion of the head of the machine showing the mechanism for shifting the stylus over the pattern.

Fig. 3 is a section on the line 3-3 of Fig. 2;

Fig. 3 is a section on the line 3 *3 of Fig. 3;

Fig. 4 is a section on the line 44 of Fig. 3 showing the means for varying the ratio be- 4 teeth, or the length from apex to apex, is the same around the entire template, and also that the pattern on the template is much larger than the pattern as reproduced in the mold. The increase in the size of the template over the pattern in the mold is desirable for a fine reproduction in the mold.

The machine is mounted on a base I provided on its upper surface with ways 2 on which is tween the movement of the stylus or pattern follower and the extent of arcuate movement of the tool;

Fig. 5 is a section on the line 55 of Fig.4;

Fig. 5 'is an enlarged section on the line 5 5 of Fig. 5;

Fig. 6 is an enlarged View of the drive mechanism for rotating the template;

Fig. 7 is an'enlarged view of the head, parts of the view being in section;

Fig. 8 is a section on the line 88 of Fig. 6;

Fig. 9 is a section on the line 9-9 of Fig. 6;

Fig. 10 is a section on the line |0-||l of 9 Fig. llv is a view looking downwardly from the plane indicated by the line in Fig. 6;

Fig. 12 is a view looking from the rear or lefthand side of the machine, the location ofthis view being indicated by the line |2|2 on Fig. 1;

Fig. 13 is an enlarged View along the line |3-- |3 of Fig. 12;

Figs. l4 and 15 are sections on the lines |4-- I4 and |5--|5 respectively of Fig. 13 and I Fig. 16 is a view of a simple but typical form of irregular tread design. In this view is shown the engraved. surface of the mold which is the obverse of the design on the tire. The design conforms to the template which hasbeen illustrated in other views.

Referring first to Fig. 16: This view shows a fragment only of a mold surface such as may be cut, and illustrates the manner in which the various units of length may be scattered over a portion of a tire. I It will be appreciated that this is only a fragment of a typical variable pitch tread design and represents only a small portion of the complete circumference. In this particular segment of the design there are shown a plurality of units of varying pitches indicated by L for large, M for medium and S for small. In this particular tire design the same arrangement of large, medium and small units is not repeated around the tire for at other portions of the tire the arrangement is quite different. I p

This particular design 'has been selected because it is a popular saw tooth tread design and is quite simple andeasy to'follow. The line p represents the split or parting line of the mold, each section of a complete mold containing four ribs a, b, c, and d which create the grooves in the tire tread. Between these ribs are the low areas 12, w, m, y and 2, which form the ribs in the finished tire, which areas represent the stock slidably mounted the carriage 3 in the center of which is the post 5 carrying the rotatable table 6. The mold section A is clamped to the table as indicated in Fig. l of the drawing. To adjust the table for molds of diifering diameters the underside of the carriage is provided with racks 8 which are engaged by pinions 9 on a shaft ||l extending through the base. Any means may be provided for moving the table, the crank arm l2 and the power cylinder |3 being shown for this purpose The table is mounted on the carriage by-a frictionless bearing |5 and on theunderside of the table is the circular rack l6 which rotates the table as cutting progresses, through a pinion I8 having an elongated shank grooved to receive a bearing collar 20 fixed to the carriage. The pinion I8 is feathered on the forward end of an elongated drive shaft 2|, the inner end of the shaft being mounted in an elongated bearing block 22 mounted at the rear of the bed I.

On the shaft 2| adjacent bearing 22 is the table driving gear 3|) and on the rear projecting end of the shaft 2| is the gear 32 which, through mechanism to be described, plate T.

The machine shown herein is intended to be driven by a motor 35 mounted on a hollow stanchion 36 on the bed plate I. This stanchion is a heavy casting which houses the motor and the drive elements for the table. It is broken away in Fig. l to disclose some of the mecha nism therein. It is desirable to provide for selective high and low speeds'for rotating'themold and the template and for this purpose mounted on the motor shaft 38 are the large and small pinions 39 and 40 which are designed to mesh with the idle gears 4| and 42. The larger gear 42 is always in mesh with the gear 30 which is of sufiicient width to permit the shifting of the idle gear assembly. The gears 4| and 42"arecarried by a sleeve 44 slidably mountedon an idle shaft 45 which is mounted in a U-shaped bracket 46 carried by the bearing block 22.

Slidably mounted on the bracket 46 is a carriage composed of the two plates 48 and 49, the latter having a rib engaging a. corresponding rib in the bracket 46. Projecting from the plate 48- is a pin 50 which enters the space between the provide for hand'operation as well as motor cp eration because'the machinist may desire to'go over the mold to touch up certain'portions' of the design in the mold- For this purpose the shaft 2| has secured on its innerextremity a hand wheel 58 and the-gear 30 is not mounted directly on the shaft 2|. but is fixed to one'element of a positive clutch 59, so that in hand operation the machinist is not required to'tur'n the motor and the intermediate gearing. Clutches rotates the temfor this purpose are wellk-nownand therefore details thereofarenot shown; r

The cutting tool and template and the means for drivingthem are mounted on'a head which is vertically 'adju'stableon guides 6-'I-' car ried on the face of the stanchion 36. shaft 62, the lower end of which engages-thehead andthe upper endof which is journalled inthe top of the stanchion provide the means- A threaded which projects-over them'old, the lower forwa-rd cornerof' the castingsupporting the cutting tool Kflwhich oscillates about the point K' located during'cuttingatthe center-0f curvature' of'that portion; of the mold which is being engraved; This center is located with respect "to-thea mold: by adjusting the carriage '3 and, the head 60. The template T is rotatedin precise timed rela*' tion to therotation of the mold by the gear 32, which meshes with a large gear: '65. carried on a'bearing. G6. The bearing ears. slidably mountedin a slot 63 formed in the upper portion. of; a swinging arm -61 which is-rotatable about the bearing 22. 68 held on the rearendof the shaft. 69: by; a nut Ill. The shaft 69 drives the template through theintermediate gearing. to be described. Iniorder-that the gear Biwill'meshwith thezgears 32 and 68 at all elevations of, the head,.the arm 61? is rotatably adjusted aroundtheaxesof the shaft 2t and isheldin adjusted position. bybolts I2v threaded? into the, bearing 2.2-"and the rear. of vthe. base. The. bolts pass througharcuate slot'srw in the arm above: and below. the center of rota;- tion of the arm. 1

The shaft69 is supported on' roller bearings. It, the bearing to the. left as viewedinFigs- L and: 6 beingrcarried in an arm I5 depending from'a. large housing'lii'. which isattached to the'head. :At' its.-..otherend the shaft 69' is mounted. in'a bracket 'I-8..carried by-the he'ad'.i:.. Between th'ei brackets-t 'IlandfIB there is keyed to.ethe1S1'laft'.-' E519:- ailong. driving gear 80,. i

1 Spacedabove the gear and. parallel to the face thereof is the sliding gear-changing shaft 82;by which the pitchof-thepattern is changed. Thisis anzidle-shaft andismounted for lengthwisehsliding movement in a bearing 83 in the armfIEzand in a bearing 85 in the: bracket I8. To, keep this-shaft fromturning'in: its bearings, a; key186i and keyways are provided between the shafti82 andthe bearing 85. This shaft carries three intermediate change gearswhich varythe ratio; of, movement of the template-T. with the rotary advance of the mold A.. .The gears are threeyinnumber. because the machine. shown anddescribedis intended'to cut threedifferent lengths ofipatt'ern units,:butif four or more lengths of unitswere to be cut thetransmission would be redesigned for that. type of tread design.

The intermediate change gears are designated fromileft' to right inorder of their size as 90, 9I and'QLthesegears, being mounted to rotate freely=-orr:frictionless.. bearings 9 l and 92*.fixed to. the shaft.8'2.. In order that the pitch line of the :three gears may coincide with the pitch line of the gear 8fiyby-whichthey are driven-the shaft is progressively stepped down from left'to rightfasshown in Fig. 10: providing the hubs 90 The gear 65 meshes with a pinion 6 g'lband 92*" on whichth mounted;

respective bearings are The shaft 82 is shifted-to make theappropri ate change in the transmission between themold:

the-side thereof at the point. where it passes:

through the bearing '85 is'provided: with. three shallow; sockets Ill!!- corresponding to three post-- tionsin'which the shaft is to be held, and in: thesid'e" of thebearing is located a ball or other: spring-held-detent I02 which snaps into one; of'. thesockets liltwhen the shaft 82 is. correctly positioned I r Above: the shaft 82 islocatedthe. template. sup--v portingsh'aft: lflfi which is. mounted at -its. rear pend: in a roller bearing. I06 in. the housing 1.6..-

Keyed'to the shaft I05 is a sleeve I021: to which; are welded the three. driven gears: '0 III and I I2 which increase in.diameterprogressivelyfrom left to right and are designed to engage with; gears 99.; 9 Land; 92 respectively,.. depending upon the position of'theshaft'. 82. As shown. in: the: drawing,- the gears 9i and .H I are in... mesh and.-

- therefore the shaft I051 andithe template' -.are..ro".--

tating at. the'intermediate speed which: would reproduce in. the mold pattern units of inter.-- mediate length. When the gears 92 and. I I2 are in mesh the template'rotates, atits slowestspeedand, as themold-isrotating'at a constantspeed this setting of." the change .gearsproducesinthe mold pattern, units of the maximum pitch or arcuateslength. When the gears 99 and H0? are; engaged the template will rotate at its hi hest speed and; therefore pattern units of short-length will be reproduced... 1 v I Atthis point it is'necessary to refer to an important. element of the invention. which makes it possible for the machinst to cut anycombina tion of long, medium or short pattern unit-s the mold and yet to have the design come out per: fectly with each cutting; around the mold'matchring with the Iothercuttings; This requires-opera:- tions of the utmost precision, otherwise va1 costly mold will be ruined. It will; be. recalled, in. this. connection that the. machineis designedasowthat the machinist may cut at onelevel abouttthe entire circumference, of the mold without shifting to another level.. Allof the gearing; fromxthe. mold table,.rotat,-.

\ ing gear I8 and rack I6 through thetrain ofgearing up to the'shaft 69'and thence through the variable transmission provided bythe largegears 80, intermediate gears 99.! and 92 to the: gears H0, III. and I I2 is accurately cut. The gearsSlJ,

, 91 and 92. and the gears H0; II! and H2 are so cut'that the shaft 82 cannot be shifted except: at a definite division of the completecycle of rotaze tionof the shaft Hi5. This result may be accomplished by. making thev numbers of gear teethii on the gears IIiI, III and I I2inultiples ofa common denominator. For example, if the teeth; in gears H0, I1 I and H2 are 90, 100 andllO, respectively; the teeth will be in alignment across the gears at 10 points only and it isonly at-these points that the intermediate gears will engage with any one of the upper gears. Of course the same result may be accomplished by adopting any common denominator;

Ten has beeni chosen for the'common-d'enom-- inator of the teeth in the three gears shown herein and on the rear side of the gear IIO are located ten equally spaced pins I03 (Fig. 9) which are so located that only when one of these pins I03 is in register with a master pin I04 mounted in the side of the housing I6 adjacent the face of the gear I I will the teeth on the several gears be in alignment at lowermost points in the gears I I0, III and H2 where they will be engaged by the gears 90, SI and 92,respectively. s

As it is desirable to change the pitch of the pattern units at definite points in the complete cycle of the mold table, the machinist cannot make a shift in the pitch of the. cutting teeth except at points which may be determined in advance and thus the pattern cut during one revolution of the mold will coincide with the pattern cut during the other revolutions. To keep track of the points at which the pitchchange occurs, the machinist marks on the table below the mold the approximate points at which the change should be made and as the tab-1e rotates and as these marks approacha stationary point he. prepares to make the shift in the transmission but can only do so when one of the pins I03 comes into alignment with the master pin I04.

Keyed to the shaft I beyond the sleeve I0! is an indexing sleeve II4, the forward edge portion of which is marked ofi" with'a scale divided into degrees for accurate setting of the template T. Over the shaft I05 and positioned directly against the sleeve I I4 is a template holding sleeve indicated as a whole by the numeral H5. The rear end of the sleeve H5 is reduced to the same outer diameter as the indexing sleeve H4 and through this part of the sleeve is threaded a set screw II6 which fixes the sleeve I I5 to the. shaft. On the edge of this portion of the sleeve H5 is placed a mark III which cooperates with the scale on the indexing sleeve. The' machinist will be able to adjust the template about the shaft to a definite position by loosening the screw I I6 and shifting the sleeve II5 about the shaft until the marker III comes to the correct'place on the scale. This refinement of the machine may be used when the machinist finds it, necessar to remount a mold for recutting .a portion of the pattern in the mold and it enables him. to set the template accurately for this purpose to correspond to his original cutting.

The larger portion I I8 of the sleeve is provided with a circumferential recess I20 on its front face, the remainder of the sleeve-being reduced to receive the template T whichvis an outer sleeve fitting over the main portionof the sleeve II5, the inner end of the template being held in' position by a bolt I2I passing through the overhanging portion II8 and entering a threaded hole in the template.

The outer or far end of the shaft I05 is reduced as shown at I24 where it is received in a roller bearing I25 mounted in a passage I25 formed in an upwardly extending arm of an angular bracket I28. The outer end of the passage is internally threaded and in this portion is received the threaded plug I30, the inner end of which holds the bearing I25 in place. A lock washer I3I is threaded on the extended end of the plug I39 and is held in position by a set screw I32.

The bracket I28 has a forwardly extending arm I34 which is channeled to fit a rib or guideway I35 which is formed on the lower outer cor-- ner of the head 60. Set screws I36 passing through the top and side of the arm I34 clamp the bracket in position on the guideway.

the template oil the sleeve I I5. As the template.

is located at a definite point on the sleeve I I5' by the bolt I2I, it is always in fixed relation to the shaft m5. 7 y

The head 60 is formed with two-parallel spaced arms, the arm towardthe template being designated on Fig. 3 as I40, and the opposite arm as MI. The lower forward ends of these arms are formed with downwardly extending lugs I44 in which are located aligned roller bearings I45 which form the pivot point K for the cutting tool K. In these bearings are mounted the ends of pins I46 and I4! which form the pivotal bearingfor the cutting tool carriage or sector.

The sector or tool carriage is made up of two parallel. plates..l52 and I53, the former being adjacent the arm I40and the latter adjacent the arm I4 I. The plate IL52 receives the threaded end of pin I46 and the plate I53 receives'the threaded end of pin I4'I. Between the plates I52 and, I53 is fixed the spindle bearing block I55 in which is rotatably mounted the spindle I56 which drives the cutting tool K through gearing in the head of the carriage. This mechanism'is well known in the art and is not shown. The outer.

end of the spindle is provided with the stepped pulleys I58 by which the spindle and cutting tool are rotated at. high speed, from a power source, by the belt I50.

r The plate I 53.is formed along its upper edge on an arc and is stepped back as shown at IBI in Fig. 3 and overlapping, this portion of the plate is the arc-shaped guide rail I62 which steadies v tion by the series the tool carriage in its oscillating movement about center K. The upper. rear edge of the plate I53 is machine finished and bears against a machinefinished strip I64 set inthe arm I4 I.

The plate I52 is formed on a much shorter radius than the plate I53 and around the. upper edge of the plate is provided. the arcuate. rib I65 which serves to locate the propelling unit'for the tool carriage. This propellin unit or driver for the tool carriage is given the general reference numeral I68. It is a generally arc-shaped member, the lower edge of which is formed witharib I69 fitting a ainst the rib I55 and held inposi of bolts I10 shown in Figs. 3 and4. p I r It will be recalled that in the general discussion it was stated that a machine embodying this invention should have some provision for varying the stroke of the cutting tool as it sweeps in an are over the surfaceof the mold with relation to the movement of the stylus over thetemplate. This was to provide for variable sizes of templates, it being impractical to make all templates on the same scale because of difierences in tread designs. Italso provides for cutting molds of difierent' sizes from the same template. If templates of clifierent scales were employed without means for varying the are over which the cutting tool is moved thereby the tread design would not be correctly reproduced in the mold, and likewise if the same template were. used for difierent size molds the treaddesign would be. incorrectly reproduced. .The propeller or. driver for the cutting tool in this machine is equipped with means for reducing or. enlarging the stroke of, the tool with relation to the amplitude of stylus movement induced by the rotating template. This will now be described:

The driver IE8 is formed with a centrally '10-.

arre s 9 .cated i-rib .II2which is held against the plate 452 :as described. Above the rib the driver is Drovided with two parallel oppositely facing walls, theleft-hand wall in Fig. 3 being designated as I14 and the right-hand wall-as I15. The opposing races of these walls are engravedwith a plurality of finely cut arcuate grooves I18, and

thelong arm of which extends over the space between the walls I14 and I15. Likewise, but .reversely positioned on the inner edge of the wall 'I'I5,,is attachedthe angular plate I82 which overlies the space'betweenthe walls I14 and I15 in the opposite direction. These plates are identical except for their reverse positioning.

Each plate is provided with along vertical slot I84 and the face of each plate is formed with aplurality of horizontal grooves I85. Located against the rear of the plate I80 is a block I86 and against the rear wall of the plate I82 is a block I 81. Each block has a tongue which engages the slot I84 andfrom'this tongue extends .a screw I88. Received over the screw is a plate I88, the rear face of which is ribbed to fit in several of the grooves I85. A nut I90 threaded onthe end of the screwholds theblockassembly in its adjusted position on the plate IE0 or I82 'as the .casemay be. Extending into each block I86 or I8! is a bolt I92 which, through a washer I94, secures the end of a driving band to each block.

' As shown in Figs. 2 and 4, there are twoparallel driving bands which oscillate the tool carriage, the one band exerting apull to the rear to rotate the tool carriage in a counterclockwise direction, as viewed in .Fig. 1, and the other exerting a pull to the front to, rock the tool carriage in a clockwise direction. I The bands are pulled to and fro by the stylus or pattern'follower through the mechanism to be described. The pull to the rear or left of the machine as shown in Fig. 1 which 'lowersjthe' cutting tool in the mold is exerted by the ban dv2llo which is attached at its outer end tothe'block- I 86 on the plate I80. The pull to the frontor right of the machine as shown in Fig. 1, which raises the cutting tool in the mold, is exerted by the band 2M which is "attached at its :outer :en'dto the block 16 1- on the plate I82. As ;sh'own in Figs. Z' and 3, these bands lie side by :s'ide and bear 'upon the band 1 T9, the bands 2'00 and 2.0 I wrapping about'the band 119 as the tool icarriage issoscillated. 1

The driving bands Ziiil'and 23 are attached to .opposite..ends:of .a long plate bearing the general .reteren'ce'znumeral .204 which overlies the band wlzlrficandltheztwobands 2E0 and 2llI. This plate I -is:best1shown'in,Figsizsande. I-thas a long cenon a bracket 2.38 mounted on the head 60.

10 the plate 204 is formed by asupplemental plate 226 welded to the end of the main body of the plate andon the end of 206 is a depending lug 208 through which is threaded a bolt 209 held in position by. the nut 2III. The inner end'of this "bolt is flattened and the end of the band 2M is 1 anchored to the bolt 269 by a second bolt 2I I. Thus, as the plate 204 is moved back and forth between the walls I14 and I15, the tool carriage will be rocked about its pivot K.

. The end of plate 204 adjacen't the pin 205 is providedwith an upstanding lug H2 and at the opposite end is a second lug 2I3, These lugs are employed to fasten the plate 204 to a reciprocating plate 229, the ends of which are provided with upstanding ears 22-I opposed to the lugs2l2 and 2I 3.- Near theendsof the plate 22!! are located long-slots 2l6 which are for the purpose of adjusting the height of the horizontal .plate 204,

bolts 2 I'I- passing through the ears22l and into the. slots. By this means the plate 204 maybe vertically adjusted so that its lower surface is always tangentto the upper surface of thebands .288 and 2M at whatever height the adjustable band I'Hlmay be located.

When the machinist desires to change thearc of the cutting tool, he will unfasten the ends of the bands 28f} andZOI from their blocks I86 and i8? and remove one of the plates Iflilor I82. He

may then remove the band II9 from the slots in WhlChll', may be situated and reposition it in.an other pair of slots closer to or more remote vfrom the pivot K, He then replaces the plate in the rocker and lowers the driving plate ZMtobring it to a position of tangency with the plate H9.

The plate 229 is formed onits outer ,face with two arms 222 which rest on the top of .a slide 225. Extending from one arm across the arms 222 is a bridge piece 223, the legs of which are turned as shown in Fig. 4 and fastened to the arms .222 and to the slide 225 by bolts 224. I I

The slide 225 is mounted vior' reciprocating movement on a dovetailed guideway 230 set in the face of the arm I 40 on theheadfill, the guideway being shimmed by a gib 231 shown in Fig. 3,.

This slide is moved to and fro to rock the tool carriage by a hand lever 235 which is pivoted at 236 to a double link 23! whichis in turn pivoted The main arm of lever 235 is provided with aslot 2.39 in which is slidably receiveda pin-assemblyind-icated as a Wholeby the numeral 246.-

This pin assembly is shown in detail in Fig.3. It-comprises a T-bolt 24-2 the head of which slides ina corresponding-1y shaped longitudinal slot .243 located in the slide 225. The shank of the bolt 242 extends through a block 245 in wh-ich is ,located the ball bearing "246. Over the bearing is a sleeve 24'! having a reduced extension providing a shoulder 228, and having its outer extremity threaded. The extension passes through the slot 239 in the lever 235 and on the outer end of the extension is threaded the nut 250 which bears upon a washer 25I wihic-hrests upon the upper surface of the arm 235. A nut 252 on the end of the pin 24,2 drawsthe pin assembly together to lock it to the slide 225. By this means the location of the arm 235 relative to the slide may be adjusted.

The end of the lever arm 235 is .forked asshown at 2.55 and pivoted at this pointonpin25fiis the swinging operating handle .25! by which themachinist moves the slide 22.5 and the parts carried thereby to .rock the tool carriage. The purpose of hinging the handle .25?! is so that it may be raised as shown in Figs. 1 and 7 when the machine is idle or when the machinist is making ready. The purpose of providing the fore-andaft adjustment of the pin assembly 242 is to permit the machinist to locate the operatin lever for its most convenient position. The machinist usually operates the lever with one hand and, while the motor may be inactive to rotate the mold table, he will operate the hand Wheel 58 with the other hand.

.-To limit the movement of the slide 225, a rod 260 having a head at its outer end is slidably received in a passage in the slide, the rearward extension of this rod passing through a bracket 26! on the head 60. Nuts 2E2 threaded on the rod 260 form stops which prevent the slide from being moved beyond the limits set thereby.

On the face of the slide 225 is a dovetailed rib 265 on which is slidably mounted the carriage 266 which supports the stylus or pattern follower. It is necessary for the machinist to adjust the position of the slide 225 before starting each operation to assure that the position of the cutting tool is properly located with respect to the position of the stylus on the template T. If the relation of these parts were not correctly made before cutting starts the tread pattern would not be correctly located in the mold. For this purpose a tie rod 268 is fixed in the forward end of the stylus carriage 266 and extends into a bracket 269 formed as a part of the slide 225. The end of the rod 268 is threaded and nuts 21E] hold the carriage 266 in its correct adjusted position on the slide 225.

From the carriage 266 is extended rearwardly of the machine the rigid arm 212 in the outer end of which is located a housing 213 which is held in position by the clamp ring 214. This housing is provided with a vertical passage to receive the stylus 215 which is a long pin, the lower end of which rides in the grooves or low places in the template. The pin is clamped in the housing by a set screw 216 so that it may be lifted out of housing when a template is changed or when the stylus is to be shifted from one groove to another of the template.

While the machinist will shift the stylus over the template by the hand lever as cutting proceeds, it is desirable to provide means to assist the machinist in following the pattern on the template. For this purpose a pneumatic cylinder is provided which can be selectively operated to press the stylus toward either side of the raised formations in the pattern on the template. Such a cylinder is mounted on the head 60, as shown at 285, the piston rod 281 being extended and adjustably fixed by the nuts 232 to an extension 283 from the bridge piece 223. As shown in Fig. 7, the cylinder is arranged so that by shifting the pressure-supply pipe 284 from one inlet 285 to the other inlet 285' the pressure exerted by the cylinder will urge the stylus either to the right or to the left.

Operation It is believed that the operation of the machine will have been made clear but the following will give a brief resume of the principal parts and functions thereof.

Before the machinist starts the operation of engraving the mold the ratio of amplitude of the cutting tool with the width of the pattern in the template together with the diameter of the cutter and the diameter of the stylus have been predetermined. The machine is then set up to suit these specifications. The machinist then Sets the "the machinist marks on the table the approximate points at which the pitch of the design will be changed so that as the table approaches'a point where the change is to be made he will shift the transmission, but as he can only makethe-shift when one of the pins I03 on gear Hi) coincides with the master pin I 04 he cannot make the shift except at points which will insure that th'edesign comes out perfectly.

Because of this arrangement he may start one groove or level of cutting and continue'at that level around the entire mold, making the-pitch changes as they occur. When he has cut all around the mold he shifts the stylus into the next groove and starts the cutting at the next level. When the pitch changes occur during this cutting operation he makes the necessary changes in the transmission at the same points that he made the changes in the first cutting and as he makes the changes at the same point in cutting each round, the variations in the tread design will always align across the mold.

During the cutting operation he moves the stylus back and forth in the groove until the stock is cut away and in this operation he uses the hand lever 235, assisted by the pneumatic cylinder. He may rotate the table through the motor or through the hand wheel 58 as he may see fit.

It will be seen that the machine provides for a combination of automatic and hand operation but that the organization is such that the machinist is relieved of much of the labor formerly required to cut an intricate pattern accurately and continuously at one level. The machine is so designed that, by following a simple procedure. the machine must correctly reproduce the desired variable pitch, non-skid tread design.

While the machine has been shown and accurately described in great detail, it will be un derstood that details are not essential to a realization of the benefits of the invention and that changes and modifications may be made without departure from the basic principles of the invention as set forth in the claims. While the machine is especially designed for a rotating template, this is not essential and the template may be of any type as is well known in the art. The invention is also illustrated in connection with cutting the curved surface of the tread but it may be modified to cut plane surfaces such as may 00- cur at the shoulder to the tire mold.

What is claimed is: l

1. A tire mold engraving machine comprising the combination of a rotatable mold supporting table, means for rotating the table, a rotatable shaft, a template, a positive drive between said template and said shaft, said template carrying a pattern for the design to be cut in the mold a movable cutting tool for the mold, a stylus in cohtact with the template and connections between the stylus and the cutting tool to move the latter to reproduce the pattern in the mold, an elongated single gear connected to and driven in unison with the rotation of the table, a plurality of gears of graduated sizes fixed to the rotatable shaft for driving the template, a shiftable shaft, and a set of idler gears fixed to said shiftable shaft in constant mesh with the single gear and shiftable along the gear while in mesh therewith to be brought into mesh with the plurality of gears selectively, the plurality of gears being pro'-" vided with numbers of teeth which are multiples of a common denominator and are in alignment only at predetermined spaced points about the gears, whereby said idler gears may be shifted only at equal divisions of the complete cycles of the table and the rotatable shaft, the relation of the gears being such that the shift from the engaged gear to the next selected gear is substantially instantaneous while said idler gears are in said constant mesh to maintain constant alignment.

'2. A tire mold engraving machine comprising the combination of a rotatable mold supporting table, means for rotating the table, a rotatable shaft, a template, a positive drive between said template and said shaft, said template carrying a pattern for the design to be cut in the mold, a movable cutting tool for the mold, a stylus in contact with the template and connections between the stylus and the cutting tool to move the latter to reproduce the pattern in the mold, an elongated single gear connected to and driven in unison with the rotation of the table, a plurality of gears of raduated sizes fixed to the rotatable shaft for driving the template, a shiftable shaft, a set of idler gears fixed to said shiftable shaft in constant mesh with the single gear and shiftable 14 along the gear while in mesh therewith to be brought into mesh with the plurality of gears selectively, the plurality of gears being provided with numbers of teeth which are multiples of a oommon'denominator and are in alignment only at predetermined spaced points about the gears, whereby said idler gears may be shifted only at equal divisions of the complete cycles of the table and the rotatable shaft, the relation of the gears being such that the shift from the engaged gear to the next selected gear is substantially instantaneous while said idler gears are in said constant mesh to maintain constant alignment, and means associated with the plurality of gears to indicate when the teeth are in alignment.

ARTHUR H. KIEHL.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,505,579 Breitenstein Aug. 19, 1924 1,797,139 Gorton Mar. 17, 1931 1,974,919 Harris et a1 Sept. 25, 1934 2,143,258 Bickel Jan. 10, 1939 

